Five-Year Naturalistic Follow-Up of Patients with Cannabis Use Disorder: Psychiatric Outcomes

Abstract

Objective: Cannabis use disorder (CUD) is increasingly prevalent and often co-occurs with psychiatric and legal complications. While cross-sectional associations between CUD and mental illness are well-documented, longitudinal data on the clinical and forensic trajectories of affected individuals remain limited, particularly in real-world settings. 
Methods: This naturalistic follow-up study tracked 51 male patients diagnosed with CUD over a five-year period. Data were collected via structured telephone interviews and hospital records, assessing substance use patterns, psychiatric diagnoses, Alcohol and Substance Addiction Treatment Center (AMATEM) admissions, and legal outcomes. Psychiatric comorbidities were evaluated using medical records, and substance use severity was assessed using the Addiction Profile Index (API). 
Results: Over five years, 82.4% of participants continued substance use, with synthetic cannabinoids being the most frequently used substance (76.5%). More than half (64.7%) developed a psychiatric diagnosis, most commonly depression and anxiety. Synthetic cannabinoid use was significantly different in individuals with psychiatric comorbidity (p = .033). AMATEM admissions declined over time but remained higher in patients with psychiatric diagnoses (Year × Diagnosis interaction: F = 2.600, p = .037). Nearly half experienced judicial psychiatric evaluations, and 23.5% had a history of incarceration. 
Conclusions: CUD is associated with persistent substance use, high rates of psychiatric comorbidity, and substantial legal-system involvement. Synthetic cannabinoids appear to exacerbate psychiatric outcomes. Long-term, integrated interventions are needed to address dual-diagnosis and reduce forensic burden.

Keywords

• Cannabis use disorder
• Synthetic cannabinoids
• Psychiatric comorbidity
• Substance use
• Longitudinal study

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